Smooth operation of the National Airspace System depends on the ability of flights to take off on time. Deicing is necessary at airports located throughout the northern third of the United States and at airports around the world at comparable latitudes. In these regions, a snowstorm or other cold-weather event can severely disrupt the carefully planned flight schedules at busy airports and impact air travelers throughout the country and around the world. In particular, a storm may cause substantial delays in the departure of flights due to the need for deicing prior to take-off. The extra time needed for an aircraft to be deiced (including waiting time) is extremely difficult to predict.
In general, the deicing process works as follows. An airplane is assigned to a deicing pad to be deiced. A deicing pad has multiple positions where the aircraft can be deiced. The positions can be of different sizes. (Some airports have more than one deicing pad, each containing several deicing positions.) An airplane is driven or towed to the queue of the assigned deicing pad and waits for a sufficiently large position to become available. Once an appropriate position is open, the leading aircraft in the queue taxis into that position. The airplane is then sprayed with a mix of chemicals combined to accomplish the rapid melting of ice, snow, or freezing rain that has accumulated on the aircraft. Moreover, supplementary chemicals may be sprayed to prevent additional accumulation. Once an aircraft is in a deicing position, the time required to spray a particular aircraft is a function of its size, the experienced efficiency of the specific deicing position, the accumulation of ice/snow on the aircraft, and the severity of the snowstorm/weather event.